Sure, its formulaic, but personally I think there is an element of spoof in it. Look at some of the dance routines. Especially the one where they are in a log cabin. They are not taking themselves too seriously here. And it does have a charm about it. My favorite song in it is the one about going to Chandala. And the scene where he enters her window about 16 stories up - it is completely ludicrous but is hugely entertaining and I feel for the right reasons.
Amir Khan also appeared earlier in "andaaz apna apna" which was very much a comedy, allthough it did tend to veer to much towards farce at times.
Although there was some sort of an action story and a moral theme to it, i think much of it was meant to be a light comedy romance, and those parts of the film worked quite nicely.
Sure its not a particularly memorable film and isnt ground breaking cinema, but its not actually a bad film, as long as you arent expecting too much out of it. And its quite watchable.